1. Field of Invention
The invention relates to a sewing machine capable of embroidering, an apparatus for processing embroidery data, and a medium for storing embroidery design data, more particularly to a technology that allows embroidery designs and a net embroidering area to be displayed on a screen, when embroidering a cloth set on an embroidery frame of the sewing machine, by finding the net embroidering area in the embroidery frame, that is, the area in which embroidering can be accomplished. The net embroidering area enables embroidering, as the presser foot used to hold the cloth and the embroidery frame do not interfere with each other.
2. Description of Related Art
There are sewing machines capable of embroidering, such as dedicated embroidering machines, and electronic sewing machines capable of embroidering, that are already in use. An electronic sewing machine capable of embroidering, uses a device respectively for feeding an embroidery cloth independently in each of the X and Y directions. The device is removably attached to the ordinary electronic sewing machine. Each such embroiderable sewing machine is provided with a means for storing data for many embroidery designs (embroidery data and design display data or embroidery data), a display unit, and a display control unit. The design data storing means may be provided in the control unit or provided as a removable ROM card to the control unit. In recent years, an embroidering system composed of plural embroidering machines controlled by a computer has been used. Hereafter, embroidery designs will be referred to simply as designs.
In such an embroidering system, an embroidery design is edited prior to the actual embroidering. In the editing process, the design is displayed on a display screen, together with an embroidery frame pattern as needed. The design is expanded or shrunk on the screen and moved within the embroidery frame. After the editing process, the embroidering begins using the design.
On the other hand, an embroidery cloth is set on the embroidery frame (including an outer frame and an inner frame fit in the outer frame with the object cloth set therebetween). The embroidery frame is driven independently in each of the X and Y directions according to the embroidery data. The embroidering presser foot has an L-shaped portion (side view) extended downward, then forward. A ring-like pressing portion (a needle is passed through this portion) is formed at a stepped-down portion of the L-shaped portion at the tip of the presser foot. Consequently, when the embroidery frame is moved forward and the embroidery frame and the presser foot come closer to each other, the bottom of the L-shaped portion of the presser foot and the rear portion of the inner periphery outline of the embroidery frame interfere each other.
In the case of the automatic embroidering machine disclosed, for example, in Unexamined Published Japanese Patent Application No. 1-213455(U.S. Pat. No. 4,960,061), the machine is composed so that data of a plurality of designs is stored in a design memory and data of the embroidery frame shape is stored in a frame pattern memory in advance. Then, both the design and the embroidery frame pattern are displayed on a display screen while the design is edited. In this case, however, the outline of the embroidery frame is not displayed. In addition, no consideration is made for the interference that occurs between the embroidery frame and the presser foot.
As described above, the bottom of the L-shaped portion of the presser foot and the rear inner periphery of the embroidery frame interfere with each other when the embroidery frame is moved close to the presser rod with respect to an object cloth set on the embroidery frame. Sometimes, therefore, embroidering is disabled partially in the inner periphery outline of the embroidery frame. This is why an invalid area of about 2 to 3 cm in width is generated around the inner rear portion of the embroidery frame. Embroidering is disabled completely in the invalid area. The net embroidering area in which embroidering is enabled, without interference between the presser foot and the embroidery frame, thus becomes narrower than the inner peripheral outline of the embroidery frame.
Like the conventional embroidering machine, a design may not be embroidered just as edited due to the interference between the embroidery frame and the presser foot even when the design is edited so as to be fit in the embroidery frame on a screen on which both design and embroidery frame (or shape) are displayed.
To avoid such a problem, therefore, it is necessary to move the embroidery frame according to the embroidery data used for the actual embroidering, thereby to check for the existence of interference between the embroidery frame and the presser foot. If any interference is found, the design must be edited again or the starting point for embroidering must be moved to change the position of the design with respect to the embroidery frame. The efficiency and productivity of the embroidering work is thus lowered significantly. And, even when editing a design, it may be necessary to edit the design by intuition to prevent the interference between the embroidery frame and the presser foot. As a result, the efficiency of the editing work is also increased significantly.